PHYS 1000 Lecture 10: Chapter 10 Notes

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tanbuffalo207

12 Feb 2018

School

University of Windsor

Department

Physics

Course

PHYS 1000

Professor

Mr.Mark Lubrick

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Document Summary

There is likely several tens of sextillions (1021) of stars in the universe. Parallax: look at the apparent motion of an object against a distant background from 2 vantage points; knowing from baseline allows calculation of distance. *distance (in parsecs) = 1/parallax (in arc seconds)* Where 1 parsec is 206, 265 au or 3. 1 x 1016 m or 3. 3 light years. Nearest star to the sun: proxima centauri, which is a member of a 3-star system: alpha centauri complex. The 30 closest stars to the sun *diagram*. A star has 2 velocity components: radical velocity velocity towards us along the line of sight (doppler effect) transverse velocity velocity perpendicular to our line of sight (parallax corrected) Ba(cid:396)(cid:374)a(cid:396)d"s sta(cid:396) has the la(cid:396)gest proper motion the actual shift of the star in the sky (after correcting for parallax). Luminosity, or absolute brightness, is a measure of the total power radiated by a star.

Related Questions

An extrasolar planet can be detected by observing the wobble itproduces on the star around which it revolves. Suppose anextrasolar planet of mass mb revolves around its star of mass ma .If no external force acts on this simple two-object system, thenits CM is stationary. Assume ma and mb are in circular orbits withradii ra and rb about the system's CM.

(a) Show that ra =(mb/ma)rb

(b) Now consider a Sun-like star and a single planet with the samecharacteristics as Jupiter. That is, mb = (1.0 x 10^-3)ma and theplanet has an orbital radius of 8.0 x 10^11 meters. Determine theradius ra of the star's orbit about the system's CM.

(c) When viewed from Earth, the distant system appears to wobbleover a distance of 2ra . If astronomers are able to detect angulardisplacements ? of about 1 milliarcsec (1 arcsec = 1/3600 of adegree), from what distance d (in light years) can the star'swobble be detected (1 ly = 9.46 x 10^15 m)?

(d) That star nearest to our Sun is about 4 ly away. Assuming starsare uniformly distributed throughout our region of the Milky WayGalaxy, about how many stars can this technique be applied to inthe search for extrasolar planetary systems?

(a) Show that ra =(mb/ma)rb

(b) Now consider a Sun-like star and a single planet with thesame characteristics as Jupiter. That is, mb = (1.0 x 10-3)ma andthe planet has an orbital radius of 8.0 x 1011 meters. Determinethe radius ra of the star's orbit about the system's CM.

(c) When viewed from Earth, the distant system appears towobble over a distance of 2ra . If astronomers are able to detectangular displacements ? of about 1 milliarcsec (1 arcsec = 1/3600of a degree), from what distance d (in light years) canthe star's wobble be detected (1 ly = 9.46 x 1015 m)?

(d) That star nearest to our Sun is about 4 ly away. Assumingstars are uniformly distributed throughout our region of the MilkyWay Galaxy, about how many stars can this technique be applied toin the search for extrasolar planetary systems?

An extrasolar planet can be detected by observing the wobble itproduces on the star around which it revolves. Suppose anextrasolar planet of mass mb revolves around its star of mass ma .If no external force acts on this simple two-object system, thenits CM is stationary. Assume ma and mb are in circular orbits withradii ra and rb about the system's CM.

(a) Show that ra =(mb/ma)rb

(b) Now consider a Sun-like star and a single planet with the samecharacteristics as Jupiter. That is, mb = (1.0 x 10-3)ma and theplanet has an orbital radius of 8.0 x 1011 meters. Determine theradius ra of the star's orbit about the system's CM.

(c) When viewed from Earth, the distant system appears to wobbleover a distance of 2ra . If astronomers are able to detect angulardisplacements ? of about 1 milliarcsec (1 arcsec = 1/3600 of adegree), from what distance d (in light years) can the star'swobble be detected (1 ly = 9.46 x 1015 m)?

(d) That star nearest to our Sun is about 4 ly away. Assuming starsare uniformly distributed throughout our region of the Milky WayGalaxy, about how many stars can this technique be applied to inthe search for extrasolar planetary systems?

PHYS 1000 Lecture 10: Chapter 10 Notes

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